Muffler



y 9,1939. E. D. LATULIPPE 2,158,030

MUFFLER Original FiIed Jule, 1935 Sheets-Sheet l Inventor Attorney y 1939- E. D. LATULIPPE 2,158,030

MUFFLER Original Filed July 8, 1935 2 Sheets-Sheet 2 I II Attorney Patented May 9, 1939 UNITED STATES PATENT OFFICE MUFFLER Refiledfor abandoned application Serial No.

30,249, July 8, 1935.

This application August 31, 1936, Serial No. 98,817. Renewed June 11, 1937. In Canada June 28, 1935 4 Claims.

This application is refiled for abandoned application Serial No. 30,249, filed July 8, ,1935.

This invention relates to exhaust muillers for internal combustion engines, especially high speed aeroplane engines, and it comprises a mufiier or silencer including (1) a main full length exhaust passage having an intake opening at the front end of the muflier adapted to be connected to an engine exhaust pipe and a discharge opening at the rear end of the muffler through which the exhaust gases pass directly to atmosphere after traversing said passage; (2) a plurality of muflling bafiles spaced along the length of said passage; and (3) a back pressure relief system through which the back pressure developed in the main passage is relieved to atmosphere in a novel manner.

Mufliers designed in accordance with this invention have been used successfully on high speed aeroplane engines and have given remarkably efiicient results in respect to absorbingthe energy and muiiling the noise of the exhaust gases without causing troublesome back pressure in the exhaust pipe. It appears that these improved results are due largely to the quiet and efficient manner in which the back pressure developed in the main exhaust passage by the flow retarding 7 effect of the baflies is quickly relieved to atmosphere through the back pressure relief system provided for this purpose. In any event, it has been found that, when the back pressure in the main exhaust passages is relieved in accordance with this invention, the noise deadening efficiency due to the flow retarding and energy ab- 5 sorbing effect of the baffles may be substantially increased by restricting the flow passages of the baflles to a much greater degree than would otherwise be feasible. Another advantage of the muflier design provided in accordance with this 0 invention is that the capacity of the back pressure system and the size of the flow passages provided in the bailles may be readily predetermined in accordance with the speed and power characteristics of the engine to which the muffler is to be applied so that both noise and back pressure are reduced to a far greater degree than is possible with any known type of muiller.

In the preferred embodiment of this invention the back pressure relief system includes a longitudinally extending relief conduit centered within the main exhaust passage of the mufiler. The front end of the conduit is spaced a suitable distance from the intake opening of the main passage and is blocked by a deflecting wall or baffle by which the'exhaust gases entering the muffler through the intake opening are deflected into the portion of the main exhaust passage surrounding the conduit instead of being permitted to flow directly through said conduit. The rearend of the pressure relief conduit is open to atmosphere and is disposed within the discharge opening of the main exhaust passage so that a strong suction is created in the relief conduit by the suction inducing effect of the gases discharged from the main exhaust passage. At suitable intervals along the length of the mufiler the relief conduit is placed in direct communication with the surrounding portion of the main exhaust passage by suitable relief vents forming part of the back pressure relief system. Certain of these vents are located directly in advance of each of the mufiler bailles which are spaced along that portion of the main exhaust passage which surrounds the relief conduit. The front section of the main exhaust passage which extends from the inlet to the first baifie is formed to provide an expansion chamber which assists in absorbing the noise producing energy of the exhaust gases traversing said passage. The rear section of the main exhaust passage which extends from the last baffle to the outlet is preferably made of substantially fish-tail configuration to further assist in diminishing the energy and noise producing effect of the gases discharged through said outlet. The extreme rear end portion of the relief conduit is preferably made of gradually diminishing depth and gradually increasing width toward the discharge opening of the main passage so that the shape of this portion of the relief conduit corresponds substantially to the shape of the surrounding fish-tail portion of the muffler casing.

Reference will now be had to the accompanying drawings, in which Fig. 1 is a top plan view of the mufller.

Fig. 2 is a side elevational view of the same.

Fig. 3 is an enlarged longitudinal section, partly broken away.

Fig. 4 is a vertical longitudinal section through the entire muflier.

Fig. 5 is a fragmentary rear end elevation.

Fig. 6 is a fragmentary elevation of the forward end of the interior back pressure relief conduit.

Fig. '7 is a fragmentary horizontal section through the rear end of the muffler.

Fig. 8 is a transverse section on line 8-8 of Fig. 3, and

Fig. 9 is a transverse section on line 9-9 of Fig. 3.

In these drawings my improved muffler is gen- )r in) .inlet I! through which the exhaust gases pass from the exhaust pipe of the engine into the main mufller exhaust passage IIa which extends the full length of the muffler casing. The front section I6 is shaped so that the inlet II is eccentrically disposed with respect to the longitudinal axis of the passage I'Ia and lies mainly above said axis. The portion of section I6 which lies between the cylindrical ends I 6a. and I I is tapered so that it gradually increases in depth toward the front end of the intermediate section I5.

The rear section I8 of the mufller casing consists of two integrally connected portions I9 and which are tapered so that this section of the casing is substantially of fish-tail configuration.

In this connection it will be noted that the portion I9 is a conical portion tapering inwardly from the front end of section I8 to an intermediate point where it joins the portion 20. The latter is made of gradually decreasing depth and gradually increasing width toward the rear end of the section I8 to provide a narrow elongated discharge opening 2I.

A longitudinally extending back pressure relief conduit B is substantially centered within the main exhaust passage I'Ia. This conduit consists of two sections indicated at 23 and 24. The section 23 is a tubular section which gradually increases in diameter toward its rear end which projects into the rear casing section I8 and is joined to the front end of the companion conduit section 24. The latter consists of two portions 25 and 26, the former being of tubular configuration and the latter being shaped to conform to the fish-tail configuration of the surrounding portion 20 of the casing section I8. The rear end of the conduit section 24 terminates in an elongated discharge opening 21 which is located in and conforms to the previously mentioned discharge opening 2I.

The front end of the'relief conduit section 23 terminates adjacent the front end of the casing section I5 and is blocked by a conical baiile 29. The gases enteringthe muffler through the inlet I'I impinge against this bafile and are deflected into the portion of the main passage I'Ia, which surrounds the conduit B instead of being permitted to pass directly through said conduit to the discharge opening 21. A plurality of muffler baflles 3| are spaced along the portion of the main exhaust passage I'Ia which lies between the relief conduit section 23 and the casing section I5. Each bafiie comprises an annular sheet metal disk slitted radially to provide a plurality of vanes 3Ia which are bent at an angle to the general plane of the disk to provide flow passages of suitable area. In practice the direction and extent of the inclination of the vanes 3i is predetermined to suit the requirements of the engine to which the rnuflier is applied. If desired, the inclination of the vanes may be such as to reverse the direction of the whirl imparted to the gases flowing through the bafiled portion of the main exhaust passage.

Between each pair of baffles 3i the wall of th e conduit section 23 is provided with a suitable number of slits 33 having their rear edges bent inwardly to form deflecting lips directed toward the front end of the mufiler. These slits afford back pressure relief vents through which the back pressure created by and in front of each baflle 3| is relieved to atmosphere via the main relief conduit B. The effective area of the vents afforded by each of theslits 33 depends upon the extent to which the rear edge of the slit is bent inwardly toward the central axis of the relief conduit B, and this may be predetermined in relation to the size of the flow passages provided in the baflies 3| to give the maximum efficiency with respect to absorbing the energy and deadening the noise of the exhaust from the particular type of engine to which the muffler is applied. The conduit section 34 is also provided with vents 33.

The front end of the relief conduit section 23 is notched to provide openings 28 which, in conjunction with the deflector 29, afiord relief passages in advance of the first baiiie 3| which serve the same purpose as the previously mentioned relief passages or vents 33.

A relatively large emergency pressure relief opening 35 is formed in the lower portion of the front casing section I6 and'is normally closed by a hinged valve plate 36. The latter is yieldingly held in closed position by a suitable spring device 31 so that it will open automatically when the pressure in the exhaust passage IIa exceeds a predetermined value.

When the mufiler described herein is in use the exhaust gases entering through the inlet II are expanded as they pass through the casing section I6 to the front end of the casing section I5. These gases impinge against the deflector 29 and are deflected into the portion of the main exhaust passage which surrounds the pressure relief conduit B. The back pressure causedby the flow retarding effect of the first bafiie 3I is quickly relieved to atmosphere via the relief passages 28 and the relief conduit B. In like manner I the back pressure caused by the flow retarding effect of each of the remaining baffles 3I is relieved to atmosphere via the slits or vents 33 and the relief conduit B. The gases flowing past the vanes of the bailles 3| are given a whirling motion which assists in absorbing the energy of the gases and diminishing the noise of the exhaust.

The flow of gases from the main exhaust passage I'Ia through the discharge opening 2I induces a strong suction in the relief conduit B which materially accelerates the rate at which the back pressure is relieved through this conduit. The shape of the casing section I8 and the conduit section 24 also assists the baffles and the back pressure relief system in diminishing the force and noise of the gases discharged through the outlets 2| and 21.

While the emergency relief valve is shown as an automatic valve, it is obvious that suitable operating means may be attached to this valve to provide for manual operation thereof whenever it is desirable or necessary to permit the exhaust to escape from the muifler at this point.

Having described the essential features and a preferred embodiment of this invention it will be understood that various modifications and rearrangements of the parts may be resorted to within the scope and spirit of the invention as defined by the appended claims.

Having thus described my invention, what I claim is:

1. A muflier for internal combustion engines comprising a casing affording a full length main exhaust passage having an intake opening at the front end of the casing and a discharge opening at the rear end of the casing, a longitudinally extending back pressure relief conduit arranged in said passage, the front end of said conduit being blocked by a deflecting wall or battle by which the exhaust gases entering the mufller through the intake opening are directed into the portion of the main exhaust passage end of the conduit being open and positioned immediately adjacent the extreme rear end of the casing so that the escape of gases through the rear end of the.

conduit is not impeded by back pressure in the main exhaust passage and a plurality of mufliing baffles spaced along the portion of the main exhaust passage surrounding said conduit, eachof said baflles comprising an annular sheet metal disc slitted radially to provide a plurality of vanes bent at an angle to the general plane of the disc.

2. A mufiier as set forth in claim 1 in which the relief conduit is made of gradually increasing area from the front end to a point beyond the rearmost bafiie of the main exhaust passage, the remaining portion of the relief conduit, together with the surrounding portion of the main exhaust passage, being made of gradually diminishing depth and gradually increasing width toward the rear discharge openings thereof.

3. A muiiler for internal combustion engines comprising a casing affording a full length main exhaust passage having an intake opening at the front end of the casing and a discharge opening at the rear end of the casing, said casing comprising front, intermediate and rear sections, said front section being of gradually increasing area from the intake opening to the front end of the intermediate section which is of uniform area throughout its length and said rear section comprising a cylindrical portion gradually decreasing in circumference from the rear end of the intermediate section to a point intermediate the length of said rear section,the remaining portion of said rear section being made of gradually diminishing depth and gradually increasing width toward the outlet at the rear end of the casing, a back pressure relief conduit arranged in said main exhaust passage and extending from a point adjacent the rear end of the front casing section to a point immediately adjacent the extreme rear end of the casing, said conduit having the front end thereof blocked by a defleeting wall or bafile preventing direct flow therethrough and having the rear end open to provide an outlet through which gases entering said conduit are discharged to atmosphere without interference by the back pressure developed in the main exhaust passage, mufliing bafiies placed along the length of the main exhaust passage surrounding said conduit and back pressure relief vents placing the interior of the conduit in communication with surrounding portions of the main exhaust passage located between and rearwardly of said bafi'les.

4. An exhaust mufiier for internal combustion engines includinga full length main exhaust passage having an intake opening at the front end of the mufiier and a discharge opening at the rear end of the muflier, a conduit extending longitudinally of said passage to provide a back pressure relief passage through which back pressure developed in the main passage is relieved directly to atmosphere at the rear end of the muffler, the front end of said conduit bein blocked by a deflecting wall or bafiie by which the exhaust gases enteringthe mufilerthrough the intake opening are directed into the portion of the main exhaust passage surrounding the conduit instead of being permitted to flow directly through said conduit, said deflecting wall or baffie at the front end of the relief conduit comprising' a hollow cone shaped member having its apex directed towards the inlet, the front end of the .)conduit being fitted in the larger end of said member in direct contact therewith, and being notched to provide relief vents lying wholly within said member, the rear end of said conduit being open and positioned adjacent the extreme end of the mufiler so that the escape of gases through the rear end of the conduit is not impeded by back pressure in the main exhaust passage, mufiling baflles located in the space between said conduit and the surrounding wall of the main passage, and back pressure relief vents placing the interior of the relief conduit in communication with the surrounding portion of the main exhaust passage at different points along the length of said passage. 

